POS0173 DATA-DRIVEN MRI DEFINITIONS FOR ACTIVE AND STRUCTURAL SACROILIAC JOINT LESIONS IN JUVENILE SPONDYLOARTHRITIS TYPICAL OF AXIAL DISEASE
Authors: P. F. Weiss, T. G. Brandon, A. Aggarwal, R. Burgos-Vargas, R. A. Colbert, G. Horneff, R. Joos, R. Laxer, K. Minden, A. Ravelli, N. Ruperto, J. Smith, M. L. Stoll, S. M. Tse, F. Van den Bosch, R. G. Lambert, D. M. Biko, N. A. Chauvin, M. L. Francavilla, J. L. Jaremko, N. Herregods, O. Kasapcopur, M. Yildiz, A. M. Hendry, W. P. Maksymowych
Journal: Annals of the Rheumatic Diseases (2022)

Background For classification in juvenile spondyloarthritis (JSpA), it is important to develop cut-offs for active and structural lesions typical of axial disease on MRI that are readily and consistently interpreted. Since the maturing sacroiliac joint (SIJ) looks different from the adult SIJ, the criteria developed for positive MRI in adults may not be applicable in JSpA. Objectives As part of a study developing classification criteria for axial disease in JSpA, we aimed to determine quantitative SIJ imaging lesion cut-offs for inflammatory and structural lesions typical of axial JSpA using majority imaging expert decision as the reference criterion. Methods Subjects were a retrospective cohort of children with SpA who met the provisional Pediatric Rheumatology International Trials Organization criteria for enthesitis/spondylitis-related juvenile idiopathic arthritis or had a rheumatologist JSpA diagnosis. All subjects had symptom onset prior to age 18 years and underwent MRI as part of a diagnostic evaluation for axial disease. To enable SIJ quadrant-based scoring, all MRIs included semi-coronal slices through the cartilaginous part of the joint on fluid sensitive sequences and on T1-weighted sequences for the assessment of inflammation and structural lesions, respectively. MRIs were reviewed by 6 musculoskeletal imaging experts who were blinded to clinical details. MRI evaluation of the SIJ was based on standardized lesion definitions that were decided by consensus of the central imaging team and represented a mix of definitions from ASAS and the Juvenile Arthritis MRI Score Outcome Measures in Rheumatology working group. Using a web-based interface, raters globally assessed the presence or absence of lesions typical of axial SpA and performed SIJ quadrant or joint based scoring. Lesion scores were generated by averaging the scores of all raters. Sensitivity and specificity of lesion cut-offs were calculated using rater majority (≥4/6 raters) on a global assessment of the presence/absence of active or structural lesions typical of axial SpA with high confidence (confidence of ±3 or stronger on confidence scale from -5, “Definitely No”, to +5, “Definitely Yes”) as the reference standard. Results Imaging from 243 subjects, 61% male, median age 14.9 years, had sequences available for detailed MRI scoring. Active inflammatory lesion typical of axial disease in JSpA was defined as bone marrow edema (BME) in at least 3 SIJ quadrants (sensitivity 98.6%, specificity 96.5%). For structural lesion typical of axial JSpA, the optimal cut-off was erosion in at least 3 quadrants or at least one of the following lesions in at least 2 SIJ quadrants: sclerosis, fat lesion, backfill, ankylosis (sensitivity 98.6%, specificity 95.5%). Conclusion We propose data-driven cut-offs for active inflammatory and structural lesions on MRI typical of axial disease in JSpA that have high specificity and sensitivity using central imaging global assessment as the reference standard. Table 1. Performance of cut-offs for inflammatory and structural lesions of axial disease Cut-offs for number of SIJ quadrants (any location) Sensitivity (95% CI) Specificity (95% CI) Definite active lesion BME score ≥2 100 (95.0-100) 93.5 (88.7-96.7) BME score ≥3 98.6 (92.5-100) 96.5 (92.5-98.7) BME, same location on ≥3 consecutive slices 88.6 (78.7-94.9) 98.8 (95.8-99.9) Definite structural lesion Erosion ≥2 95.7 (88-99.1) 96.8 (92.7-99) Erosion, same location on ≥2 consecutive slices 94.3 (86-98.4) 98.1 (94.5-99.6) Erosion ≥3 91.4 (82.3-96.8) 98.7 (95.4-99.8) Sclerosis ≥2 62.9 (50.5-74.1) 98.1 (94.5-99.6) Fat lesion ≥2 22.9 (13.7-34.4%) 98.7 (95.4-99.8%) Backfill ≥2 20 (11.4-31.3) 100 (97.7-100) Ankylosis ≥2 1.3 (0.2-4.7) 100 (94.9-100) ANY of the following in ≥2 SIJ quadrants: erosion, sclerosis, fat lesion, backfill, ankylosis 98.6 (92.3-100) 93.6 (88.5-96.9) Erosion ≥3 quadrants OR ≥2 quadrants of at least one of the following lesions: sclerosis, fat, backfill, ankylosis 98.6 (92.3-100.0) 95.5 (91.0-98.2) Disclosure of Interests Pamela F. Weiss Consultant of: Pfizer Novartis Biogen Lilly (All &lt;$5K in the past fiscal year), Timothy G. Brandon: None declared, Amita Aggarwal: None declared, Ruben Burgos-Vargas Speakers bureau: Not in the last three years. Novartis, Consultant of: Not in the last four years. BMS, Lilly, Novartis, Robert A. Colbert: None declared, Gerd Horneff Speakers bureau: Pfizer, Novartis, Janssen, Chugai, Abbvie, Grant/research support from: Pfizer, Novartis, MSD, Chugai, Roche, Abbvie, Rik Joos Speakers bureau: Galapagos, Pfizer, AbbVie, Novartis, Amgen, BMS, Lilly, Grant/research support from: Pfizer, AbbVie, Roche, Ronald Laxer Consultant of: Abbvie, Novartis, Sobi, Sanofi, Eli Lilly Canada, Eli Lilly, Kirsten Minden Speakers bureau: Pfizer, Novartis, Consultant of: Pfizer, Novartis, Angelo Ravelli Speakers bureau: Abbvie, Novartis, SOBI, Angelini, Reckitt-Benkiser, Roche, Pfizer, Alexion, Grant/research support from: Novartis, Pfizer, Nicolino Ruperto Speakers bureau: NR has received honoraria for consultancies or speaker bureaus from the following pharmaceutical companies in the past 3 years: 2 Bridge, Amgen, AstraZeneca, Aurinia, Bayer, Brystol Myers and Squibb, Celgene, inMed, Cambridge Healthcare Research, Domain Therapeutic, EMD Serono, Glaxo Smith Kline, Idorsia, Janssen, Eli Lilly, Novartis, Pfizer, Sobi, UCB., Consultant of: NR has received honoraria for consultancies or speaker bureaus from the following pharmaceutical companies in the past 3 years: 2 Bridge, Amgen, AstraZeneca, Aurinia, Bayer, Brystol Myers and Squibb, Celgene, inMed, Cambridge Healthcare Research, Domain Therapeutic, EMD Serono, Glaxo Smith Kline, Idorsia, Janssen, Eli Lilly, Novartis, Pfizer, Sobi, UCB., Grant/research support from: The IRCCS Istituto Giannina Gaslini (IGG), where NR works as full-time public employee has received contributions from the following industries in the last 3 years: Bristol Myers and Squibb, Eli-Lilly, F Hoffmann-La Roche, Novartis, Pfizer, Sobi. This funding has been reinvested for the research activities of the hospital in a fully independent manner, without any commitment with third parties., Judith Smith Consultant of: Consulting panel of pediatric rheumatologists identifying issues in juvenile spondyloarthritis for Novartis. Paid &lt; $5000, Matthew L. Stoll Consultant of: Currently consulting for Novartis, Shirley ML Tse: None declared, Filip van den Bosch Speakers bureau: Abbvie, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer, UCB, Paid instructor for: Amgen, Eli Lilly, Consultant of: Abbvie, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer, UCB, Robert G Lambert Paid instructor for: Novartis, Consultant of: CARE Arthritis, Calyx, Image Analysis Group, Novartis, David M. Biko Employee of: Merck (1998-2000), Nancy A. Chauvin Employee of: Forest Pharmaceuticals - Research scientist (1996) and Novartis - Pharmaceutical sales representative (1997), Michael L. Francavilla: None declared, Jacob L Jaremko: None declared, Nele Herregods: None declared, Ozgur Kasapcopur Speakers bureau: Pfizer, Abbvie, Novartis and Roche, Mehmet YILDIZ: None declared, Alison M. Hendry: None declared, Walter P Maksymowych Speakers bureau: Abbvie, Eli-Lilly, Janssen, Novartis, Pfizer, UCB Pharma, Consultant of: AbbVie, Boehringer Ingelheim, Celgene, Eli Lilly, Galapagos, Janssen, Novartis, Pfizer, UCB Pharma, Grant/research support from: Abbvie, Novartis, Pfizer